The present invention relates to an ink jet recording apparatus and an ink jet recording method. Particularly, the invention relates to an ink jet recording apparatus provided with a heater, and to an ink jet recording method performed with respect to coated printing paper having low water absorbability.
An ink jet recording method is a printing method which performs printing by ejecting minute ink droplets from a printing head toward a recording medium, such as paper or the like. Since the ink used in the ink jet recording method is ejected from the printing head, it is necessary for the ink to have low viscosity, and thus ink having high water content is used.
Accordingly, as problems of the ink jet recording method, the occurrence of feathering, the occurrence of bleeding, the drop in density, the degradation in a color developing property, the degradation in fixing property (drying property), and the occurrence of a cockling curl may be exemplified. As a method of resolving theses defects, a thermal drying system is generally suggested.
For example, Japanese Patent Publication No. 2004-142385A discloses an ink jet printer in which a heater is mounted on a head carriage, and a printing surface is heated and dried by a pressure contact roller while performing printing. However, in such an ink jet printer, since the pressure contact roller contacts the printing surface right after performing printing, a blur may occur before being dried.
Japanese Patent Publication No. 10-86353A discloses an ink jet printer in which a rod-shaped halogen heater is disposed on a back face of a printing surface so as to accelerate evaporation. In such an ink jet printer, the quick start is possible by using the halogen heater, but in order to heat the printing surface at the sheet surface temperature of 200° C. for the purpose of completely evaporating a liquid component of ink, a heating process is performed by applying energy of about 200 W on an average. Accordingly, the atmosphere temperature rises, so that even ink in the printing head is dried, which causes clogging. In addition, the temperature of each component rises, a heat radiating mechanism needs to be provided in the printer, which results in an increase of a cost or size.
Japanese Patent Publication No. 10-323974A discloses an ink jet printer in which an infrared ray heater having a specific peak wavelength is disposed on a back face of a carrying path so as to perform a heating process. In such an ink jet printer, in order to improve an efficiency of the infrared ray heater, the distance between the heater surface and the paper surface is set to 0.35 mm (the relatively short distance). Since the temperature of the heater becomes the high temperature of 170° C., paper dust is dropped from the back face of the paper, which may cause a fire. In addition, since the heating is performed from the back face of the printing surface, a drying efficiency is lowered, the printing head is always in a dried state by a hot air, and the clogging occurs.
An ink jet recording method is a printing method which performs printing by ejecting minute ink droplets from a printing head toward a recording medium, such as paper or the like. Since the ink used in the ink jet recording method is ejected from the printing head, it is necessary for the ink to have low viscosity, and thus ink having high water content is used.
On the other hand, dedicated paper having high water absorbability is used as the recording medium to obtain a high quality printed image. However, in order to attain sufficient ink absorption, a coated amount for the ink absorbing layer must be increased. In addition, in order to allow the ink absorbing layer to be transparent, fine powder silica or alumina is used as a raw material, which leads to an increase of a cost. As a result, this increase of a cost becomes an obstacle that restricts a use of a user.
Although common paper such as copy paper or the like is cheap, since it has lower water absorbability than the above dedicated paper, it is not originally appropriate for the recording medium of the ink jet recording method. Various ink has been developed for ensuring a high quality image with respect to the cheap common paper, but it is originally very difficult for the common paper to attain the image quality of the dedicated paper.
As paper cheaper than the common paper such as the copy paper or the like, there is coated printing paper. This coated paper is a composite sheet obtained by coating both faces or one face of the base paper with a coated color being a kind of coating material for the purpose of an improvement of printability. The coated paper is provided for only printing sheet. Since the coated paper is used in a recording method which uses ink having high viscosity and does not require water absorbability, optimization is made in the coated paper such that it is excellent in a fixing property or color developing property. In the coated paper, a thick ink absorbing layer like the above dedicated paper or a high-graded fine particle having high transparency is not necessary. In addition, production facilities are provided so as to meet an active demand of several millions of tons for a year, so that coated paper of a high quality has been supplied very cheaply.
Since the coated paper has water absorbability lower than the common paper, it is not more appropriate than the common paper for the recording medium of the ink jet recording method. However, since the image quality of the coated paper is very high, a technology has been suggested in which the coated paper is used as the recording medium of the ink jet recording method.
For example, Japanese Patent Publication No. 2002-240411A discloses an ink jet recording method in which, after ejecting ink droplets onto an intermediate transfer medium having a transfer layer formed on a base substrate so as to form an intermediate image, the intermediate image is transferred to the transfer layer and the coated paper to obtain a final image. However, according to this technology, since the image is not directly formed on the coated paper but formed using the intermediate transfer medium, a device other than an ink jet printer is further required. That is, since a size of the printer increases and a manufacturing cost of the printer or a printing cost increases, it is not possible to achieve advantages of an ink jet recording method characterized by the simplicity and a small size.
Japanese Patent Publication No. 2001-199151A discloses another technology in which at the same time as ink ejection, an image quality improving liquid having a function for aggregating ink on the paper is sprayed so as to prevent the ink from spreading on the paper, or heat is applied to the paper during printing operation so as to support the drying treatment. However, according to this technology, the spraying of the image quality improving liquid may cause disadvantageous effects. For example, clogging of nozzles may occur due to the mist of the image quality improving liquid. Since a liquid amount on the recording medium may increase in order to spraying of the image quality improving liquid, it may not be possible to suppress bleed from occurring. Further, a dedicated capping system for handling the image quality improving liquid may be necessary.